They're pretty damn efficient and nicely modular if you're okay with not having context sensitivity. Most of the time you're okay with not have context sensitiv

They're pretty damn efficient and nicely modular if you're okay with not having context sensitivity. Most of the time you're okay with not have context sensitivity, imo. Context sensitivity as I wrote it here is the most powerful but least optimizable version. There are plenty of tricks to improve optimization. You can even write a "cut" combinatory to break backtracking. It's a huge design space. The answer to all of your questions will probably be: it depends.